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Subject[PATCH 3/6] [2.6.29] epoll: remember the event if epoll_wait returns -EFAULT
If epoll_wait returns -EFAULT, the event that was being returned when
the fault was encountered will be forgotten. This is not a big deal
since EFAULT will happen only if a buggy userspace program passes in a
bad address, in which case what happens later usually doesn't matter.
However, it is easy to remember the event for later, and this patch
makes a simple change to do that.

Signed-off-by: Tony Battersby <tonyb@cybernetics.com>
---

This patch is against 2.6.29-rc6; however, it doesn't need to go
into 2.6.29. Use the -mm version instead if applying after the other
patches in -mm.

--- a/fs/eventpoll.c 2009-02-20 16:34:02.000000000 -0500
+++ b/fs/eventpoll.c 2009-02-20 16:36:25.000000000 -0500
@@ -974,8 +974,6 @@ static int ep_send_events(struct eventpo
for (eventcnt = 0; !list_empty(&txlist) && eventcnt < maxevents;) {
epi = list_first_entry(&txlist, struct epitem, rdllink);

- list_del_init(&epi->rdllink);
-
/*
* Get the ready file event set. We can safely use the file
* because we are holding the "mtx" and this will guarantee
@@ -1000,6 +998,9 @@ static int ep_send_events(struct eventpo
epi->event.events &= EP_PRIVATE_BITS;
eventcnt++;
}
+
+ list_del_init(&epi->rdllink); /* remove from txlist */
+
/*
* At this point, noone can insert into ep->rdllist besides
* us. The epoll_ctl() callers are locked out by us holding


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